Industrial, residential and mobile, including power generation, transportation, automotive and aerospace, controls systems often require actuation of mechanical components. Mechanical components of such systems may include valves that must be actuated. Such actuation is generally accomplished via pneumatic, hydraulic or electric components and/or systems. There are generally three different remote controlled types of valve actuation.
Valve actuation may be accomplished by electric components, including permanent magnet direct current (PMDC) motors, brushless direct current (BLDC) motors, direct current stepper motors, linear or rotary solenoids. Electric actuation is susceptible to environmental temperatures and suffers from reliability issues, especially in mobile applications due to the variations in operating environment and the harsh engine compartment/under hood environment.
Valve actuation may also be accomplished by pneumatic or electro-pneumatic means using pneumatically controlled linear or rotary actuators. Such actuators may include on/off or proportional actuation. Pneumatic and electro-pneumatic systems suffer from low position accuracy due the compressible nature of the fluid, typically atmospheric air, used for actuation and the moisture generated in the air compressor system.
In addition, valves in mechanical systems may be actuated by electro-hydraulic means, using hydraulically controlled linear or rotary actuators. Such actuators may employ on/off or proportional control. Conventional electro-hydraulic actuators use oil from the engine lubricating system or other high-pressure hydraulic power assist systems. The pressures of the engine lubricating systems are in the neighborhood of 100 psi and vary with engine speed.